The study, published in the Sept. 28 issue of
The Lancet, looked at whether stem cells might improve the
current technique of "lipofilling" -- where fat is removed via
liposuction from one part of the body, purified, then injected into
another area of the body.

Doctors use lipofilling in cosmetic procedures to create
smoother skin or fuller lips. But it also has a range of medical
uses. Fat injections can help reshape the breasts in women having
reconstruction after breast cancer surgery. They can also be used
in correcting facial deformities caused by an injury or congenital
defect, or helping certain burn injuries heal.

The problem is that transferred fat often doesn't last,
explained lead researcher Dr. Stig-Frederik Kolle.

"It's unpredictable," said Kolle, of the plastic surgery department at Copenhagen University Hospital in Denmark. "And you often have to repeat the procedure to get a [satisfactory] result."

So Kolle's team tested a different approach: Take stem cells
from people's body fat and use them to "enrich" the fat tissue
being transplanted from one body area to another. Stem cells are
primitive cells that develop into more mature ones.

The researchers recruited 10 healthy volunteers who underwent
liposuction to have fat taken from the abdomen. The fat was then
purified and injected into the volunteers' upper arms. In one arm,
the fat transplant was enriched with stem cells; the other arm
received a traditional transplant.

After about four months, the researchers took MRI images of the
fat transplants, then removed them. It turned out that the stem
cell-enriched transplants had retained about 81 percent of their
initial volume, on average -- compared with only 16 percent among
the stem cell-free transplants.

Dr. J. Peter Rubin, chair of plastic surgery at the University
of Pittsburgh Medical Center, said the study is "very"
important.

"We've known that this works in animals. What's been missing is good data on humans," said Rubin, co-author of an editorial accompanying the study.

These early results offer a "proof of principle," and need to be
followed up with clinical trials of actual patients, rather than
healthy volunteers, Rubin said.

One question is whether the transplanted fat will hold up over
the long term, experts say. "We have no reason to believe that it
won't last," Kolle said, but it still needs to be shown in
studies.

And why do the added stem cells help? It's not clear, said
Kolle. One possibility is that they spur the growth of small blood
vessels and give the transplanted fat a better blood supply. The
stem cells may also develop into mature fat cells, or send out
"signals" that cause other cells -- such as fat or blood vessel
cells -- to increase in number.

As for safety, Kolle and Rubin said there is a theoretical
concern in using stem cell-enriched fat in women who've been
treated for breast cancer. Some of the benefits of stem cells --
such as releasing "growth factors" that stimulate other cells --
could potentially feed a breast cancer recurrence.

"There's no evidence to suggest that this is true," Rubin said. But it is a possibility that everyone should be aware of, he added.

Kolle agreed. "We need to move forward carefully," he said.

Even if stem cell-enriched fat transplants prove safe and long
lasting, there will be practical hurdles, since the approach would
add costs and complexity. Kolle said the process of harvesting the
stem cells, then growing and expanding them in cultures, is
actually relatively simple -- but the facilities have to be in
place.

"No, not every center will be able to do this," he said.

Still, editorial author Rubin said that new technology is
needed. Breast reconstruction, he noted, has been done by the same
methods for decades. It's possible, said Rubin, that stem cells
could help allow some women to have reconstruction done solely via
fat injections -- without the major surgery or implants used
now.

The current study was funded by the Danish Cancer Society. None
of the researchers reports any financial conflicts of interest.
Rubin has submitted a patent application for an instrument that
harvests body-fat tissue.

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